A study of the possible importance of hydroperoxides in the aquatic environment to human health will be undertaken. A method for the detection of hydroperoxides in the presence of other organic oxidants will be devised. Individual hydroperoxides will be identified by gas chromatographic - mass spectroscopic analyses on their reduction products. Photochemical and thermal mechanisms for the formation of hydroperoxides, and their reactions with steroids, other lipids, polycyclic hydrocarbons, amino acids, proteins and nucleic acid constituents will be studied.